A glass based dual band frequency selective surface for protecting systems against WLAN signals

A polarization independent, double layer frequency selective surface on glass substrate is proposed that can transmit 900 MHz and 1.8 GHz GSM bands but inhibit transmission of wireless local area network (WLAN) bands, 2.4-2.5 GHz and 4.98-5.825 GHz. A parametric analysis is conducted to tailor the resonance frequencies at WLAN bands and the effect of each geometrical parameter on band stop response is investigated. Band stop responses of each FSS layer and the double layer final design are presented both numerically and experimentally. The simulation results showed a good agreement with the experimental results and supported the polarization independent behavior. In particular, very wide rejection bands are obtained (−10 dB bandwidths more than 1.75 GHz) for the 5 GHz band, both numerically and experimentally, for vertical and horizontal polarizations, under normal incidence. The design can be used in double layer window glasses for protecting systems against interference with WLAN signals in indoor environments and buildings.